1. Field of the Invention
This invention relates to heddle frame staves, and more particularly to metallic staves of hollow construction with at least one additional member connected thereto for dampening vibrations and thereby being comparable to staves made of material having different characteristics.
2. Prior Art
In known weaving machines the heddle frame staves are of hollow metal construction to reduce weight and to achieve the highest possible bending stiffness. Light metal, hollow heddle frame staves of lightweight construction have therefore been used, but not without presenting drawbacks.
For example, such frame staves are known to emit bending vibrations which generate sound vibrations which, due to their resonance characteristics, transmit a substantial degree of sound, particularly with fast running weaving machines.
In order to minimize these unpleasant noise developments with heddle frames, vibration-dampening material has been inserted into the hollow profile of the frame staves for filling at least a part of the hollow insides thereof, such material, and which are pressing against the inner side walls of the hollow staves. This insert material will therefore dampen the aforementioned vibrations.
A known frame stave of such construction has round openings on one of its side walls into to which an insert of elastic material is pressed, the insert being in, which slightly larger than the opening so that after insertion it will expand. And, both side walls of the hollow profile stave may have opposed openings into which such an insert is placed so as to sightly protrude outwardly for serving as a guide, for example.
In another construction of a heddle frame stave, the vibration problem is solved in such a way that the distance between the side walls of the hollow profile is smaller than the thickness of the material of the insert, which will be introduced from the face side, such that the side walls will be kept in an elastically deformed shape which minimizes the development of vibrations. The expense of such measures which have been taken, however, rarely justify to the desired results.
In yet another known construction, the heddle frame stave is not hollow, but comprises a solid rail of metal having at least one recess opening outwardly and extending in the longitudinal direction of the frame stave, the recess being filled with a suitable formed body of vibration-dampening material which lies freely to the outside. The combining of the heddle frame and the dampening body can preferably be carried out by glueing. With a profile rail of double T cross-section, the known heddle frame stave has at both sides of the rail a free space between the flanges to be filled with a material which dampens the vibrations, the material preferably being of wood or synthetic material, which therefore form parts of the outside surfaces of the heddle frame stave but do not, however, provide much resistant against wear. Upon impacting the frame staves of adjacent weaving frames during the weaving process resulting in frictional wear, the stressed staves will deteriorate after a rather short time, thereby requiring additional measures, such as guides, to prevent further wear. Another disadvantage is that with a solid profiled rail having vibration-dampening materials (which may be wood) arranged on both sides of the rail to provide a solid profile, the advantage of a lightweight hollow profile is lost. Furthermore, this type of heddle frame stave is weak against torsional stress.